The study relates to vapour absorption into a falling film, where the concentration levels of absorbate and absorbent are comparable. The combined heat and mass transfer processes involved are analysed through an integral formulation of the continuity, diffusion and energy equations. Adiabatic and isothermal wall conditions are considered. The Nusselt and Sherwood numbers are expressed in terms of the non-dimensional parameters which characterize the system. It is shown that in the case of finite absorbate dilution, the lateral convective term at the free interface ought to be accounted for. The resulting transfer rates are shown to depend on both the absorbate concentration level and driving force and are significantly augmented compared to those obtained under the assumption of infinite absorbate dilution.